PortAtlas is an independent reference to network port numbers. It exists to answer three practical questions quickly: what a port is used for, whether it is risky to expose, and the exact commands needed to check or block it on Linux and Windows.
Where the data comes from
Assignments come from the IANA Service Name and Transport Protocol Port Number Registry, the authoritative list maintained by the Internet Assigned Numbers Authority. Widely used ports that have no IANA assignment are included only when they are clearly labelled as community conventions.
How pages are built
Each page is generated from the registry plus a curated set of operational notes. Every port is checked in the same way: filter out reserved and de-registered rows, merge protocols for the same number, verify the service name for each transport, and pair it with copy-ready diagnostics. The methodology page explains the filtering rules, risk ratings and command caveats in detail.
Editorial principles
- Registry first. When the registry and common usage disagree, the page says so instead of presenting one as the other.
- No invented facts. Risk ratings describe exposure patterns, not specific vulnerabilities or CVEs.
- Commands that run. Every snippet is written for a typical current Linux distribution or Windows host, and caveats such as IPv4-only iptables rules are stated on the page.
- No tracking beyond analytics. There are no accounts, newsletters or advertising scripts. Analytics is limited to Google Analytics 4 and is described in the privacy policy.
Not affiliated with IANA
PortAtlas is not affiliated with IANA, ICANN, Google or any of the vendors mentioned. Service names and trademarks belong to their respective owners. Always verify a current assignment against the official registry before making firewall changes.
Last updated 2026-10-30.